of salem



Nov. 6, 1928.

F. T. COPE FURNAGE-DOOR AND PUSHER INTERLCK Filled March 5, 1925 Patented Nov. 6, 1928.

FRANK T. COPE, or sarna/i', OHIO, .assit-inca 'To 'ran ELECTRIC f" Lesen Nran este,

summonl COMPANY,

' OF SALEM, OHO, A CORPORATION OF OHO.

Application aies Maren 5, 1925 seriaino. 13,133.

This invention relates to: electric furnaces and'more particularly to the type in which a charge is introduced through a door -by a f power operated pusher mechanism for opening the furnace doors andl operating a pusher to move the material through the furnace; and the objects'of the invention are to provide an interlock mechanism by means ofwhich the pusher cannot be operated untilthe doors are opened, thus preventing lthe pusher mechanism or the furnaceV from being damaged in the event that the operator negligently attemptsto place the `pusher. mechanism in Yoperation before the doors have been openedzr Y l v -An embodiment of the invention is illustrated in the accompanying drawing, in which, the figure is a diagrammatic view of a continuous furnace provided with door opening mechanism and pusher operating mechanism, showingt-he improved interlock applied thereto. n .p c

Similar numerals of reference indicate oorresponding parts throughout .the drawing.

A continuous furnace is indicated vat 1, provided throughout its length with a hearth 2, upon which the'material is adapted to be movedithrough the furnace, the hearth entending beyond the chargingend of the furnace as shownvat` 3, in order that the material to be ,treated'may be charged uponsaid extension of the hearth, and then pushed into the furnace by the pusher 4 as will be hereinafter described. Y

' VThe charging and discharge door openings 5 and Gare :arranged to be normally closed by the doors 7 and 8 respectively. .For thel purpose of raising and lowering the doors 7 and 8 in unison, a motor 9is mounted in a suitable location, preferably above the furnace as shown. rlhe pinion 10 upon the motor shaft meshes with a gear 11, which is provided with a threaded bore to receive the screw 12 slidably located in a bearing indicated at 13. Y

A cable 14 is connected to the top of the door 7 and extends over a pulley 15, the opposite end of the cable being connected to the adjacent end of the screw 12.

A similar cable 16 is connected tothe top of the door 8 and extends over the pulleys 17 and 18, and is attached to the other end of the screw 12. When the motor 9 is operated to raise the doors, the. screw 12 will travel toward the right pulling the cables 14 and 16 over the pulleys and raising both-of the doors in unison. Y

A bar 19 is carried by thescrew 12, and is arranged to automatically operate a series of switches which control the limit of travel of the doorsandthe interlock between.l the doors and pusher. I

`The pusher 4 is provided with a rack bar 20, meshing with a pinion 21 upon the shaft 22 which carries a gear 23 meshing with a pinion 24 upon the shaft ofthe pusher operating motor 25.

g Abar 26, similar to the bar 19, is carried by the rack bar 20 and arranged to operate switches whichV control the limit of travel l of the'pusher. r

Each of the motors 9 and 25 is illustrated as a three-phase vreversing motor. The current supply is brought in from the wires 27 and 28, the two wires 27 leading to the contact points 29 of the interlock switch y30, the blades ofwliich are connected by wires 31 with two ofthe blades of the pusher operating switch 32, while the wire 28 is connected vthe switch.. One'of the contacts 36 is con- :ff

nected by a wire 38 with the corresponding contact 37the other two contacts 37 are connected by wires 39 with the contacts 40 of the limit switch/41, the blades of which are Connectedby the wires 42, in reversev position, with thelblades of the Vlimity switch 43. The contacts 44 of the limit switch 43 are connected by the wires 45 with the two lower contacts 36 of the double throw, reversing switch 34. A wire 47 connects the upper contacts 36 and 37 of the switch 34 with the door operating motor 9 and the wires 48 connect said motor with the wires 42.

The double throw reversing switch 32 is provided with two sets of contacts 49 and 50, one of the contacts 49 being connected by a wire 51 with the corresponding Contact 50. The other two contacts 49 are connected by wires 52 with the contacts 53 of a limit switch 54 which controls the travel of the pusher 4.

lil() The blades of the switch 54 are connected by wires 55 with the blades of another limit switch 56 which controls the travel oit' the pusher in the opposite direction and wires 57 connect the wires 55 with the pusher motor 25. The contacts 58 of the switch 56 are connected Vas by the wires 59 with the two lower' contacts of the reversing switch 32, a wire 60 leading from the other Contact of the re versing switch Yto the pusher motor.

Each of the limit switches 54 and 56 is provided with a shoe 61 arranged to 'be engaged by the bar 26 to operate the switches, and each of the limit switches 4lv and 48 as well as the interlocking .switch 30' is provided with a similar shoe 62 arranged to be engaged with the sliding bar 19. Y

In operating the furnace the double throw y reversing switch 34 is thrown into the position shown in the drawing, closing the'cir cuit through the wires 45, 42 and 48 to the motor 9 to operate the motor in the direction to move the screw 12 to the right, raising the doors 7 and 8. f The parts are so located that the bar 19 Vwill engage the shoe 62 of the f limit switch 41, closing said switch just before said bar has permitted the shoe of the switch 43 to drop, opening the switch. At this time the doors are inthe opened position and the motor is thus stopped. Although the drawing shows the mechanism diagrammatically it should be understood that the shoe of thel interlockingswitch 3() is engaged lby the bar 19 as the doors reach the open position, closing the locking switch and completing the circuit through the double throwy reversing switch 32 to the pusher motor- 25.

Assuming that the switch 32 is in the posi- Y tion shown in the drawing, the motor 25 will be operated to move the pusher to the righe pushing-any material which has been placed upon the extension 3 into the furnace inthe usualmanner. lAs the bar 26 engages the shoe ofthe switch 54 to close the same and moves out of engagement with the shoe of the switch 56, permitting the same to open, pusher motor will be stopped. The switch 32 is then thrown into the opposite position en gaging `the blades with the contacts 49' to movethe pusher back to the position shown inthe drawing, aterwhichthe switch 34 is Damage to the furnace and pusher' mechai nism 1s thus eliminated, as the pusher can not be operated in either direction while the doors are open. Y

I claim 1. In combination with and a pusher for moving material intoethe furnace when the door is in theV openedposition, a motor for operating the door, a switch controlling the door motor, a motor fory op.- erating the fpusher, a switch controlling the a furnace, a door pusher motor, an interlock switch in parallel with the pushermotor'switch,a sliding bar operated by the doorfmotor, switches engaged Y by the sliding bar to stop the door motor when the door is in the fully opened or fully closed position, said sliding bar engaging the interloclr switch to close it only when the door is in the fully opened position.

2. In'combination with a furnace, a door and a pusher for moving material into the furnace when the door is in the openedposition, a motor for operating the door, a switch sok controlling the door motor, a motorI for' 'operating the` pusher, a switch controlling the pusher' motor, aninterlock switch in para1- lel with the pusher motorV switch, a

sliding l.har operated by the"` door Amotor,

switches engaged by the sliding ba1"-t.)V

stop the doorV motory when the door vis in the fully opened or fully closed'position,

' said sliding bar engaging theinterlock switch to close it only when the door is Vin the fully opened position, a SIidingbar-Operated by the pusher motor, switches engaged by thelast named sliding bar to stopthe pusher motor when" the pusher is at eitherextrcmeposition of i travel. Y v

In testimony that I claimthe above I hereunto subscribed my name.

FRANK T.. corn. y

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